Water Treatment > Quality Water Solutions > Operational Issues > Treatment Goals

Although treatment plants generally have a unique spectrum of operational and finished water goals, many plants want to improve their coagulant programs in order to accomplish one or more of the following:

• Improve clarification for solids and color removal.
• Reduce particle counts.
• Enhance cold water performance.
• Reduce production of chemical residue.
• Improve treated water stability.
• Improve filter life and efficiency.
• Make coagulants easier to use.

Balancing several of these goals simultaneously can be challenging. For example, increasing coagulant dose by 30% may lower water turbidities in cold water and increases filter run lengths, but it may boost chemical residue, demand more pH adjustment chemicals and alter the corrosion inhibitor program.

Most water utilities work hard to balance several treatment goals at once. In many cases, they use a multicoagulant approach adopted through trial and error. This may meet a plant's objectives, but it may not be highly efficient or effective.

Given the range and sophistication of the coagulants available today, they can often meet several treatment goals with a single product. Often this may mean using an enhanced coagulant. Although they may cost more than traditional aluminum and iron salts, their versatility can make them well worth the added price. Given the many available coagulants, plants should experiment with different products. While theory and lab studies can narrow the field, only in-plant testing can define how well a coagulant performs. In testing a coagulant, prioritize the treatment goals and evaluate it for 30 to 60 days during a difficult treatment period. Comparison is most meaningful if two treatment trains are available, one using the existing coagulant and the other the coagulant tested.